The Dark Wob

That's right regards coolant expansion. Easy to make a DIY expansion tank. It will be a case of keep the 13psi cap on the rad and run the overflow to a bottle mounted lower than the rad. The noise definitely sounds more valve train related and seeing as it has a timing chain and pushrods then there's always going to be chatter. The engine sounds a lot quieter and starts better since new plugs and tappet adjustment.

Update, while I remember the figures.

Along with rewiring the fan via a relay so it works properly (80w fan on bell wire was never going to be happy) I setup the carb on Roland today. He runs a lot better on 14 1/2 flats down, compared to the 22 flats or so he was on before so should be a lot better on fuel too. The fast idle being stuck on before can't have been helping either.

Oh & we lashed up a temporary bodge of an expansion bottle too. All seems good on a couple of short test runs, gets to temp & stabilises with no nasty noises, leaks or other issues. He does appear to be able to get the rear end to feel loose when hammered out of junctions now... should be safe* in Bub's hands.

I took it steady till it warmed up, second time round the block and up the hill where it stepped out was just to see if it had a bit of poke. The carb has certainly helped with running too. It feels a lot better than what it has in a long time. I was surprised at it stepping out though as it's never done it there before!

It held a steady 85 degrees under hard throttle up the steep hill too. Switching fan on bought engine temp down from over 95 with fan off at idle down to 85 comfortably quick too

Aye it seems happy enough now to me, once you've got some not leaky pipe for that expansion bottle it should be trustworthy.

It's not attached at the moment. Will be tied down with wire and a bungee cord in no time.

I'm not sure how you described plumbing that expansion bottle in from the overflow has increased coolant capacity at all? When I've had a header tank they've been T,'d into a flow or return pipe.

Just a basic overflow into which if there's too much expansion it goes into bottle then drawn back into the system or something like that. reliant 850s never had an overflow till around 1994 and then it was just a pipe off the overflow from the neck of the rad into a tank. Also mine doesn't obviously have the heater radiator either so has less coolant in the system.

Well just been for a little run through town. Didn't even need to use the fan. It sat around 85 and briefly went to 90 in traffic but airflow when moving cooled it down enough. Carb could do with a bit of tinkering but that's about it.

Sounds good. He was a lot richer before, so unscrewing the mixture nut will put him nearer where he was before if it was better then. Might be the float level or that wobbly float bowl of course.